The present invention relates to a storage controller such as a disk array apparatus, and more particularly, to a storage controller that is configured to: examine whether a file system copied from a primary volume to a secondary volume has any errors or not; enable input to and output from (I/O access to) the secondary volume if it is determined that the file system has no errors; and ensure that the file system of the secondary volume is kept as backup data.
When date from a host system such as a server or a host computer is stored in a disk array apparatus, the following operation is generally conducted for data backup: establishing a primary volume and a secondary volume in the disk array apparatus and using the secondary volume to mirror the primary volume. To “mirror” means that the secondary volume mirrors the primary volume and the content of the primary volume is reproduced in the secondary volume.
When performing data backup, a disk array apparatus controller splits the secondary volume from the primary volume (SPLIT processing) and transfers backup data from the secondary volume, that has been made static by the SPLIT processing, to a different storage resource such as a tape device or another disk array apparatus. After data backup has been completed, the disk array apparatus makes the secondary volume mirror the primary volume.
Data backup is performed in a state where the secondary volume is split from the primary volume and receives no I/O access from the host computer or the like in order to prevent data being updated during backup. Accordingly, the backup is performed at the point in time the secondary volume is split from the primary volume.
The above operation is disclosed in JP-A-2000-330730 as a difference copying system. Furthermore, as a technique to instantly make a copy of a primary volume, JP-A-2004-19213 discloses a copy volume generating method and disk device.